Correct handling of explicit -Empty:$false parameter value in New-Guid by logiclrd · Pull Request #26140 · PowerShell/PowerShell

logiclrd · 2025-10-03T03:34:48Z

Fix New-Guid's handling of -Empty to check the switch's value, rather than only its presence, allowing parameter values to be passed through easily.

PR Summary

This PR adds a test to reproduce the bug described in issue #25276, and then updates the implementation of the New-Guid cmdlet to fix the bug, making the test pass.

PR Context

Fixes #25276
Related to #25242

PR Checklist

…ng the bug described in issue PowerShell#25276. Updated the implementation in NewGuidCommand.cs to correct the handling of explicit $false values passed to -Empty, making the test pass.

logiclrd · 2025-10-03T03:37:47Z

@microsoft-github-policy-service agree

iSazonov · 2025-10-03T05:25:36Z

/azp run PowerShell-Windows-Packaging-CI, PowerShell-CI-linux-packaging

azure-pipelines · 2025-10-03T05:25:45Z

Azure Pipelines could not run because the pipeline triggers exclude this branch/path.

src/Microsoft.PowerShell.Commands.Utility/commands/utility/NewGuidCommand.cs

xtqqczze · 2025-10-04T22:22:25Z

src/Microsoft.PowerShell.Commands.Utility/commands/utility/NewGuidCommand.cs

            else
            {
-                guid = ParameterSetName is "Empty" ? Guid.Empty : Guid.NewGuid();
+                guid = Empty.ToBool() ? Guid.Empty : Guid.NewGuid();


Suggested change

guid = Empty.ToBool() ? Guid.Empty : Guid.NewGuid();

guid = Empty.IsPresent ? Guid.Empty : Guid.NewGuid();

this seems to be the more common pattern

The use of .ToBool() instead of simply checking for presence is the entire point of this PR, actually. The caller could pass in -Empty:$false, in which case it would be present, but the caller's intent is to not get the empty GUID. (By checking which ParameterSet is in effect, the previous code was in effect also just checking for the presence of the switch.)

The implementation is identical:

PowerShell/src/System.Management.Automation/engine/MshCmdlet.cs

Lines 110 to 113 in be0542b

public bool ToBool()

{

return _isPresent;

}

Actually, I agree we shouldn't use IsPresent. It may be implemented identically, but this appears to be a design error.

If it is accepted, then this PR can be rebased to use .IsSpecified. If it is not accepted, then I posit that it is essentially not important whether this PR uses .IsPresent or .ToBool() -- but that .IsPresent makes less sense since the bug being fixed in this instance is precisely related to the fact that a switch might be present with the explicit value $false.

no places that use the implicit conversion

I find 379 references to the implicit operator, for example:

PowerShell/src/System.Management.Automation/FormatAndOutput/out-console/OutConsole.cs

Lines 194 to 199 in be0542b

public SwitchParameter Paging

{

get { return _paging; }

set { _paging = value; }

}

That's really weird. To test, I deleted the operator from the source code and ran Start-PSBuild, and it built with no errors. 🤔

I didn't see errors at first. But I ran Start-PSBuild -Clean and now get error CS0029.

Ahh, fair enough.

microsoft-github-policy-service · 2025-10-06T04:49:05Z

📣 Hey @@logiclrd, how did we do? We would love to hear your feedback with the link below! 🗣️

🔗 https://aka.ms/PSRepoFeedback

Microsoft Forms

PowerShell#26140)

Added test of New-Guid -Empty:$false to New-Guid.Tests.ps1, reproduci…

eee7027

…ng the bug described in issue PowerShell#25276. Updated the implementation in NewGuidCommand.cs to correct the handling of explicit $false values passed to -Empty, making the test pass.

logiclrd changed the title ~~Correct handling explicit -Empty:$false parameter value in New-Guid~~ Correct handling of explicit -Empty:$false parameter value in New-Guid Oct 3, 2025

iSazonov added the CL-General Indicates that a PR should be marked as a general cmdlet change in the Change Log label Oct 3, 2025

xtqqczze reviewed Oct 4, 2025

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src/Microsoft.PowerShell.Commands.Utility/commands/utility/NewGuidCommand.cs Show resolved Hide resolved

xtqqczze reviewed Oct 4, 2025

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logiclrd mentioned this pull request Oct 5, 2025

Switch parameter standardization #26150

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12 tasks

iSazonov approved these changes Oct 6, 2025

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iSazonov self-assigned this Oct 6, 2025

iSazonov merged commit b5279a2 into PowerShell:master Oct 6, 2025
36 of 39 checks passed

iSazonov added Hacktoberfest Potential candidate to participate in Hacktoberfest Hacktoberfest-Accepted Accepted to participate in Hacktoberfest labels Oct 6, 2025

SIRMARGIN pushed a commit to SIRMARGIN/PowerShell that referenced this pull request Dec 12, 2025

Correct handling of explicit -Empty:$false parameter value in New-Guid (

2f033e0

PowerShell#26140)

SufficientDaikon mentioned this pull request Mar 24, 2026

Fix Get-Culture -ListAvailable:$false and Get-Location -Stack:$false #27034

Open

7 tasks

	guid = Empty.ToBool() ? Guid.Empty : Guid.NewGuid();
	guid = Empty.IsPresent ? Guid.Empty : Guid.NewGuid();

	public SwitchParameter Paging
	{
	get { return _paging; }

	set { _paging = value; }
	}

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logiclrd commented Oct 3, 2025 • edited by iSazonov Loading Uh oh! There was an error while loading. Please reload this page.

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logiclrd commented Oct 3, 2025 •

edited by iSazonov

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logiclrd Oct 5, 2025 •

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logiclrd Oct 5, 2025 •

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